Gas turbine engines, sometimes referred to as turbomachines, may be used in various environments to, among other things, generate electrical power, provide propulsion, supply compressed air for various pneumatic loads, and drive various mechanical loads. A typical gas turbine engine includes at least a compressor, a combustor, and a turbine. The compressor draws in ambient air, compresses the air, and supplies the compressed air to the combustor. The combustor receives the compressed air from the compressor, and a controlled flow of fuel from a fuel source and, via igniters, ignites the air-fuel mixture to generate high energy gas. The high energy gas is supplied to the turbine and, upon impinging blades within the turbine, causes the turbine to rotate.
The above-described turbomachine operational mode is a standard open cycle operational mode. However, some turbomachines may be configured to be selectively operated in other operational modes. For example, a turbomachine may also be configured to operate in a closed cycle mode. In this operational mode, fuel is not supplied to the combustor, and compressed air is supplied from an external compressed air source, such as bleed air from another gas turbine engine. While operating in the closed cycle mode, the compressed air that is supplied from the external source may decrease to an undesirably low pressure. When this occurs, fuel may be introduced to the turbomachine combustor and ignited to supplement the energy from the external compressed air source. This latter operational mode is sometimes referred to as a burn and bleed mode.
During burn and bleed mode operation of a turbomachine, it can be quite difficult to detect a flameout event. This is because the turbomachine speed and power may be maintained by the energy of the externally supplied compressed air. If an undetected flameout occurs during bleed and burn operation, fuel will continue to be supplied to the turbomachine, resulting in non-combusted fuel being wastefully exhausted.
Hence, there is a need for a system and method of accurately detecting a flameout condition in a turbomachine, especially during a bleed and burn operational mode. There is also a need for a system and method of determining, if a flameout condition exists, whether a relight attempt should be made. The present invention addresses one or more of these needs.